This invention relates to a desalting system utilizing solar energy as a source of heat.
The utilization of inexhaustible solar energy in place of fossil fuels, such as oil and coal limited in their reserves, is proposed in many fields and has already been put to practical use in some fields. Also in the field of the desalting art, some desalting systems utilizing solar heat have been proposed instead of the conventional multistage flash method using fossil fuels. Applicant has proposed several systems for example as disclosed in Japanese Patent Publication Nos. 3077/79, 36150/79 and 3793/81. Most of such proposed desalting systems adopt a fixed type of solar heat collector to heat seawater, so that the cost required for equipment and operation is not too high, but the amount of heat to be collected depends on the position of the sun, and particularly during the morning and evening when the position of the sun is relatively low, the amount of collected heat is small, and therefore, the temperature of seawater heated by the solar heat collectors is generally below 100.degree. C. For the above reasons, it may be necessary for the temperature of the seawater to be further increased by additionally heating by means of fossil fuels, or a decompression device such as a bleeding ejector, used.
Thus, to improve the amount of collected solar heat, a system has been proposed in which tracking type of heat collectors are used in such a way that their heat collecting planes are moved according to the movement of the sun in a day. According to this system, seawater can be heated directly or through some heat-transfer medium above 100.degree. C. For that purpose, however, it is required that concentrating type of heat collectors are used in such a way that the mirrors thereof are properly directed to the sun, each of the mirrors being provided with a respective tracking means, and the heat collectors are arranged together as a whole. Therefore, such a system becomes a considerably large-scale, and hence the cost for construction, operation and maintenance of the system will become enormous.